Image scanning apparatuses such as facsimiles, copying machines, and valuable paper reading devices irradiate light from a lighting apparatus to a document or a sheet of paper is a scanning object, cause reflected light and/or transmitted light thereof to image onto a photoelectric conversion element such as Complementary Metal-Oxide Semiconductor (CMOS) sensors or Charge-Coupled Device (CCD) sensors through an image formation element such as a lens or a mirror, and detect light information of the scanning object. In addition, image scanning apparatuses can copy a document, determine whether the sheet of paper is true or false, and determine the degree of deterioration during distribution, using image information generated from light information of the scanning object. In recent years, the miniaturization of image scanning apparatuses and speeding up of the reading speed require miniaturization and high efficiency of lighting apparatuses.
Patent Literature 1 describes a lighting apparatus in which light sources are arranged along the outer periphery of the cross section of the light guide for causing light to enter into the end portion of the light guide uniformly, and for causing light to emit efficiently to the outside.
Patent Literature 2 describes a highly efficient lighting apparatus in which light sources for emitting light in red, green and blue colors to the end portion of the light guide are arranged. The lighting apparatus can easily adjust emission colors by adjusting the amount of light emission from each light source.
Patent Literature 3 describes a lighting apparatus in which a light guide and an LED light source that transmits light in a main scanning direction are arranged. The lighting apparatus reduces its size by arranging a light blocking member in the vicinity of the light guide that emits light, and aims at uniformity in illuminance in the main scanning direction.